Solution Plasma-Synthesized Black TiO2 Nanoparticles for Solar-Thermal Water Evaporation

Black TiO2 nanoparticles (b-TiO2) with superior solar-thermal water evaporation performance are prepared using a one-step solution plasma process (SPP) in ambient conditions. It is found that radicals that are generated during SPP play a critical role in b-TiO2 formation by comparing several water-alcohol electrolyte environments for the SPP synthesis. Our results show that the radical-induced formation of a black TiO2- x layer on the Ti electrode is necessary for bTiO(2) formation, which was ignored in previous studies. A two-step mechanism for b-TiO2 formation in SPP synthesis is proposed: (I) preoxidation of a Ti electrode surface; and (II) quenching and aggregation of sputtered molten TiOx clusters to form b-TiO2 particles. The b-TiO2-loaded hydrophobic mesh exhibited high water evaporation rates in the solar-thermal water evaporation experiments, which were 1.2, 1.4, and 2.3 times higher than that of the control group without using mesh at 1000, 2000, and 5000 W.m(-2), respectively. The understanding in this study may inspire strategies for the facile synthesis of self-structured modified metal-oxide materials for more efficient solar energy harvesting in solar-thermal conversion applications.

Automated summary

Black TiO2 nanoparticles (b-TiO2) with superior solar-thermal water evaporation performance were prepared using a one-step solution plasma process (SPP). Radicals generated during SPP played a critical role in b-TiO2 formation, with a two-step mechanism proposed for its synthesis. The understanding gained from this study may inspire strategies for more efficient solar energy harvesting in solar-thermal conversion applications.